In the past several years petroleum crude oil has increased in price many-fold due to the controls in production and price levels established by the Middle East countries producing a large percentage of the world's crude oil. This has caused a significant increase in research efforts to develop alternative fuels. Among the areas investigated has been that of pulverizing coal and dispersing it in petroleum oil as an "extender" for the oil. Petroleum residual oil, as distinguished from "distillate" from which gasoline is produced, is of relatively high viscosity, e.g. 1-10 poises, and when powdered coal is added the viscosity rises rapidly with increasing concentrations of coal. At viscosities above about 5-10 poises, the liquid is too difficult to pump to consider the liquid as a practical fuel. Accordingly, it has been a difficult problem to produce easily pumpable coal in oil slurries at high coal concentrations (e.g. 50% to 60% by wt. of coal).
It is an object of this invention to provide a liquid fuel oil having the property of low viscosity. It is another object of this invention to provide a liquid fuel oil that is capable of carrying high concentrations of pulverized coal at low viscosities. Still other objects will appear from the more detailed description which follows.